DE1160234B - Fungicides - Google Patents

Description

GERMAN

PATENT OFFICE

F36575IVa / 451

REGISTRATION DATE: 17 A P R I L 1962

NOTICE
THE REGISTRATION
AND ISSUE OF
EDITORIAL: DECEMBER 27, 1963

The invention relates to fungicidal agents based on diarylazo compounds. It was found, that 4-N, N-dimethylamino-4'-hydroxyazobenzenes of the formula

Fungicides

H ₃ C

H ₃ C

N = N

OH

in which Ri for hydrogen, methyl, phenyl, hydroxyl or chlorine and Ra for hydrogen, Hydroxyl or methyl, have strong fungicidal properties and are particularly suitable for Combat. of harmful fungi on green parts of the plant. On the other hand, show the invention The substances to be used only have a low level of warm-blooded animals and phytotoxicity.

Compared to the one proposed in the Belgian patent specification for the same purpose 594 503 known coupling products of basic substituted aromatic diazonium salts the agents according to the invention are distinguished by compounds with reactive methylene groups also by a significantly lower number of warm applicants:

Paint factories Bayer Aktiengesellschaft, Leverkusen

Dr. Ewald Urbschat, Cologne-Mülheim, and Dr. Ferdinand Grewe, Burscheid, have been named as inventors

blood toxicity and better plant tolerance. The still known to be fungicidal Azo compounds in which R and Ri (cf. the formula given above) represent hydrogen atoms are the preparations to be used according to the present invention for the application Strongly superior to leaf fungi, as can be seen in the following table:

Table I.
Action against Phytophthora infestans on tomatoes

preparation
No.

Constitution Level of infestation after using the preparations in an active ingredient concentration of

O, O25o / o

0.00625%

0.003125%

H ₂ N

(CHa) ₂ N

H ₂ N

(CHb) ₂ N

100

CH ₃

100

100

100

100 30

100 36

309 770/436

I 160 234

continuation

preparation

No.

Constitution Level of infestation after using the preparations in an active ingredient concentration of

0.025%

O, O0625o / o

0.003125%

H ₂ N

(CHs) ₂ N

N = N

100

100

100

13th

From the reported results of comparative experiments it can be seen that the known substances 1, 3 and 5 have no fungicidal action against Phytophthora, while with the invention to be used products 2, 4 and 6 the Phytophthora infestation is very strongly depressed.

The compounds are produced according to processes known per se and are based on the the following representative example explained:

H ₃ C

H ₃ C

136 g (1 mol) of 4-aminodimethylaniline be in a mixture of 1000 cc of water and 225 g concentrated hydrochloric acid at 0 to 5 ⁰ C and 70 g of sodium nitrite - diazotized - dissolved in 250 cc of water. The diazonium salt solution is then allowed to flow into a solution of 120 g of resorcinol in 1200 ecm of water. After completion of the addition, the mixture with vigorous stirring until an alkaline reaction with solid sodium bicarbonate is added, stirred for several hours the precipitated dark precipitate filtered off with suction after 20 hours of standing of the mixture, thoroughly washed with water and dried at 50 to 60 ⁰ C. _{The 4-N 5} N-dimethylamino-2 ', 4'-dihydroxyazobenzene obtained in almost quantitative yield ^{decomposes when heated at about 200 °} C.

Similarly, the following compounds can be obtained:

4-N, N-dimethylamino-4'-hydroxyazobenzene,
2-N, N-dimethylamino-3'-methyl-4'-hydroxy-

azobenzene,
4-N, N-dimethylamino-3 ', 5'-dirnethyl-

4'-hydroxyazobenzene,

4-N, N-dimethylamino-3'-phenyl-4'-hydroxyazobenzene,

^ N, N-dimethylamino-3'-chloro-4'-hydroxyazobenzene,

4-N, N-diethylamino-2 ', 4'-dihydroxyazobenzene,

4-N-methylamino-3-methyl-2 ', 4'-dihydroxyazobenzene,

4-N, N-dimethylamino-3'-carboxy-4'-hydroxyazobenzene,

4-pyrrolidyl-2 ', 4'-dihydroxyazobenzene, 4-morpholyl-3', 5'-dimethyl-4-hydroxyazobenzene.

The compounds are either stretched as such or, preferably, in the customary manner Spray or dust applied.

Here, other fungicides, insecticides, acaricides, wetting agents and adhesives or others can have the effect substances that have a beneficial effect on the preparations are added.

The following example explains the invention in more detail:

example

Testing of the fungicidal effectiveness when used against Phytophthora infestans on tomatoes

Young tomato plants (Bonny Best variety) are sprayed with aqueous suspensions or emulsions of the preparations listed below. After drying of the spray coatings inoculating the plants in a moist chamber with an aqueous slurry of fungal spores and then incubated them at 18 to 20 ⁰ C and 100% relative humidity for 5 days. The infestation is then evaluated by assessing the intensity of infestation on each leaflet. The infestation level is calculated from the infestation intensity and frequency and expressed as a percentage of the infestation of the untreated control, the infestation level of which is set = 100.

The values determined are in the following table !! compiled:

5 6

Table II
Fungicidal effect against Phytophthora infestans on tomatoes

preparation

Physical Properties

Infestation level after application

of the preparations in an active ingredient concentration of

0.025% 0.00625% 0.00315%

(CHs) ₂ -N- /> -N = N- /> -OH

brown crystals (from xylene)

red crystals (from benzene)

brown crystals (from ethanol)

red crystals (from benzene) 191 to 191 (decomposition)

167 to 168 (decomposition)

149

138 (decomposition)

(CHs) ₂ -

OH

brown crystals (from ethanol)

brown crystals (from toluene) 203 (decomposition)

152 to 153

Comparative agent (zinc ethylene bis-dithiocarbamate
Control (untreated)

12th

26th

39

30th

36

13th

17th

27

66

100

Claims (1)

PATENT CLAIM: Fungicidal agents, characterized in that they contain 4-N, N-dimethylamino-4'-hydroxyazobenzenes of the formula H ₃ C H ₃ C = N ^OH in which Ri represents hydrogen, methyl, phenyl, hydroxyl or chlorine and R _{2 represents} hydrogen, hydroxyl or methyl. & 309 770/436 12.63